AX88875AP Bripeater

ASIX ELECTRONICS CORPORATION

13

3.0 Functional Description

3.1 Repeater State Machine

The repeater state machine is used to control repeater behavior, generates right signal in corresponding

states. The repeater state machine is in Idle state when there is no carrier presented on any ports . When there

is only one port has receive activity, the repeater state machine will enter Data - forwarding State to ensure

correct data forwarding to other connected ports. If collision happens anytime, The repeater state machine

detects collision then send jam pattern to all ports until collision ceases.

idle State

The idle state happens when these conditions exists:

a.

/RST is low.

b.

All CRS[4:0] are not asserted high in single chip application.

Data Forwarding State

The state happens when the condition exists:

a. Only one signal asserted among CRS[4:0] in single chip application.

The repeater state machine stores receiving packet and transmits to all other ports except for

1.

The port is jabbered.

2.

The port is isolated.

Collision State

The Collision State happens when these conditions exists:

a.

There are two or more signals asserted high among CRS[4:0] in single chip system.

b.

Only one carrier exists but RXDV still low exceeds 4 clock cycles in 100BASE-T. The

repeater sends collision pattern to all ports.

One Port Left State

The state happens only when there is no collision but still one port which experienced collision

has receive activity. The repeater remains send collision pattern to all ports except the port.

3.2 RXE /TXE CONTROL

Idle state

The repeater sends no data to any port.

RXE(ALL) = 0.

TXE(ALL) = 0.

Data Forwarding state

If ACTIVE(X) = 1, X is the local connected port,

RXE(X) = 1, RXE(ALL-X) = 0.

TXE(X) = 0, TXE(ALL-X) = 1.

Collision state

The repeater sends jam pattern to all ports.

RXE(ALL) = 0.

TXE(ALL) = 1.

One Port Left state

The repeater sends jam pattern to all other port except for the still activity port.

RXE(ALL) = 0.

TXE(ALL-X) = 1. Suppose X is the one left port.